The Microprocessor (R)evolution

This retrospective blog describes how Sven Andersson became involved in testing microprocessors in 1976, and how microprocessors have influenced his professional work for many years.

Moving to Switzerland
Two of my favorite winter activities are skiing and skating. The mountains in Sweden cannot compare to the Alps, so I found myself traveling to Austria and Switzerland every winter for one week's skiing. That was all I could afford at the time, but I always dreamed about skiing a whole winter in the Alps. That's why I started thinking about moving to Switzerland.

At the users meeting in Germany, I had met a guy working for a Swiss company (Landis & Gyr) in Zug. It had the same kind of Tektronix test equipment, and it used Motorola microprocessors. The company needed someone that could help them write test programs and I was hired. In October 1979, I packed my things and moved to Switzerland.

The photo above was taken in Zermatt in 1981 and shows me in front of the famous Matterhorn. (You will note that, unlike in the pictures with my previous blogs, there are no bell bottom trousers to be seen.)

Testing the Motorola MC68000
My first task at Landis & Gyr was to write a test program for the 16-bit Motorola MC68000 microprocessor. This was a huge device that was presented in a 64-pin dual-in-line package. This was before the introduction of surface mount devices (which would be used in later versions).

The 68000 grew out of the Motorola Advanced Computer System on Silicon (MACSS) project, which was begun in 1976 to develop an entirely new architecture without backward compatibility. This was to be a higher-power sibling complementing the eight-bit 6800 line, rather than a backward-compatible successor. In the end, the 68000 did retain a bus protocol compatibility mode for 6800 peripheral devices, and a version with an eight-bit data bus was produced. However, the designers mainly focused on the future, or forward compatibility, which gave the M68K platform a head start against later 32-bit instruction set architectures. For instance, the CPU registers were 32 bits wide, though few self-contained structures in the processor itself operated on 32 bits at a time. The MACSS team drew heavily on the influence of minicomputer processor designs, such as the PDP-11 and VAX systems, which were similarly micro-coded.

I used the same approach for writing the test program for the 68000 as I used for the 6801, and I came up with a similar test setup. This time I added an external memory in which I could store the program code executed by the microprocessor. To generate the test program, I had to write a cross assembler for the 68000.

Yes, at that time you could still write your own cross assembler, but I don't think you would do this today. The test program development was described in a document I presented at a Tektronix users meeting in Philadelphia in 1984.

Here's a hand-drawn block diagram showing the test setup.

Moving back to Sweden
After a few years in Switzerland, I came to realize that skiing was not the only thing in life, and that I missed the long summer days in Sweden. I moved back to Sweden, returned to my old job at Ericsson, and continued to write test programs for more and more complex devices.

In the mid-1980s, I came in contact with a new device called an application-specific integrated circuit (ASIC). The design department at Ericsson had just designed its first ASICs, and it was our job to test them.

I summarize my time as a component test engineer with the illustration above. After 15 years of testing components, it was time to move on to new challenges. Though I didn't know it at the time, I was soon to become an ASIC designer myself, and this will be the subject of a future retrospective.